Medium chain triglycerides (MCT) are a family of triglycerides generally containing saturated fatty acid chains of from about 8 to about 12 carbon atoms. These fatty acid chains are often predominantly caprylic acid (8-carbon) and capric acid (10-carbon) chains, with lesser amounts of caproic acid (6-carbon) and lauric acid (12-carbon) chains.
MCT have reportedly been used for parenteral nutrition in humans requiring supplemental nutrition, and are reportedly also increasingly being used in foods, drugs, and cosmetics. MCT have additionally reportedly been found to be non-toxic in acute toxicity tests for a range of animal species.
In contrast to MCT, long chain triglycerides (LCT) contain saturated and unsaturated fatty acid residues with greater than 12 carbons. Differences in fatty acid chain length and degree of saturation reportedly have been observed to lead to differences in digestion, absorption, and transport in at least some species. Specifically, for example, medium chain fatty acids (MCFAs) reportedly have been observed to have a greater tendency to enter portal blood directly and be transported to the liver for rapid oxidation, whereas long chain fatty acids (LCFAS) reportedly have been observed to have a greater tendency to be packaged into chylomicrons and transported into the lymphatic system, allowing for extensive uptake into the adipose tissue in at least some animals. MCFAs also reportedly have been observed to have a tendency to enter mitochondria independent of the camitine transport system and undergo preferential oxidation in at least some animals. Papamandjaris, et al., “Medium Chain Fatty Acid Metabolism and Energy Expenditure: Obesity Treatment Implications”, Life Sciences, 62:1203-1215 (1998). It has been hypothesized that relatively rapid metabolism of MCT may, relative to LCT, increase energy expenditure, decrease deposition of MCT into adipose tissue, and result in faster satiety in at least some species. See St-Onge, M., et al., “Physiological Effects of Medium-Chain Triglycerides: Potential Agents in the Prevention of Obesity”, P. J. Nutr., 132:329-332 (2002). See also, Rothwell, N., et al., Metabolism, 36:128-130, 1987 (reporting that feeding MCT to humans increases energy expenditure and fat oxidation, and discussing potential for use of MCT in weight management regimes). See also, Tsuji, H., et al., “Dietary Medium-Chain Triacylglycerols Suppress Accumulation of Body Fat in a Double-Blind, Controlled Trial in Healthy Men and Women”, Nutr., 131: 2853-2859 (2001) (discussing reduction of body weight and fat using MCT diet in humans). See also, Portillo, M., et al., “Energy Restriction with High-Fat Diet Enriched with Coconut Oil Gives Higher UCP1 and Lower White Fat in Rats”, Int'l J. Obes. Relat. Metab. Disord., 22: 974-979 (1998) (reporting that MCT-enriched diet is effective in stimulating uncoupling protein-1 (UCP1) expression during ad libitum feeding and preventing UCP1 down regulation during food restriction in rats). See also, Lasekan, J., et al., “Energy expenditure in rats maintained with intravenous or intragastric infusion of total parenteral nutrition solutions containing medium- or long-chain triglyceride emulsions”, J. Nutr., 122: pps. 1483-1492 (1992) (reporting lower weight gain and greater energy expenditure in rats having MCT-supplemented parenteral nutrition relative to rats having LCT-supplemented parenteral nutrition).
Despite the reported advantages of MCT, there have been difficulties in developing MCT-containing foods. Some studies, for example, have reported that MCT-containing foods tend to have poor palatability.
Thus, there continues to be a need for compositions for animal consumption, particularly those that aid in weight loss or reduction in the rate of weight gain.